Russian forces in Ukraine are suffering from “morale and discipline issues” caused at least in part by problems with their compensation, the UK Ministry of Defense said. The Russian side has suffered heavy casualties more than six months since the invasion, prompting Putin last month to order an increase in the number of military forces by 137,000 to about 1.15 million. Members of the Russian military receive a modest basic salary with “a complex variety of bonuses and allowances”, the UK Ministry of Defense said, but there have likely been problems with the payments of these combat bonuses so far. A convoy of pro-Russian troops moves along a road in Mariupol, Ukraine. (REUTERS/Chingis Kondarov) “This is likely due to inefficient military bureaucracy, the unusual legal status of the ‘special military operation’ and at least some outright corruption [among] commanders,” the UK Ministry of Defense said. UKRAINE NUCLEAR AGENCY WARNS RISK OF HYDROGEN, RADIOACTIVE LEAKS AFTER DAMAGE AT ZAPORISZIA FACILITY It is not the first time that Western military officials have noted problems of discipline in the Russian ranks. A senior US defense official told reporters in a telephone conversation in May that “unit morale and cohesion remain an issue.” “Soldiers disobeying orders or not fighting as well or as aggressively as they are told or expected — even to the point where some officers refuse to obey orders,” the official said at the time. Smoke rises from a Russian tank destroyed by Ukrainian forces on the side of a road in the Lugansk region. (ANATOLII STEPANOV/AFP via Getty Images) CLICK TO GET THE FOX NEWS APP Russia has lost between 60,000 and 80,000 troops so far in Ukraine, US officials believe. Efforts are being made to replenish their forces. “They’ve done it in part by removing the upper age limits for recruits and also by recruiting prisoners,” a senior US defense official said last month. “Many of these recruits have been observed as older, unfit and spoiled.” Paul Best is a reporter for Fox News Digital. Story tips can be sent to [email protected] and on Twitter: @KincaidBest.